#define _CRT_SECURE_NO_WARNINGS

#include<iostream>

using namespace std;

int main()
{
	double n;
	scanf("%lf", &n);

	double l = -1000, r = 1000;
	while (r - l > 1e-8)
	{
		double mid = (l + r) / 2;
		if (mid * mid * mid < n) l = mid;
		else r = mid;
	}

	printf("%lf", l);
	return 0;
}